Stones buying guideLast updated October 2026

Slate

The century roof, and a rugged, grippy floor.

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Price level
Mid-range
Best to buy
Jan–Mar, Oct–Nov
Top sources
Spain flagBrazil flagIndia flagChina flagUK flag
Stacks of split slate roofing tiles

Photo: Dennis G. Jarvis, CC BY-SA 2.0

Overview

What is slate?

Slate forms when fine clay and shale are metamorphosed under low heat and pressure. The minerals realign in parallel planes, so slate splits cleanly into thin, flat sheets, perfect for roofs. Good roofing slate is almost impervious to water and can last a century or more.

Floor and wall slates come riven (natural cleft surface) or honed. Quality varies widely: watch for iron pyrite, which rusts, and for flaky, delaminating stone.

Rock type
Metamorphic (from shale and mudstone)
Hardness
2.5 to 4 Mohs
Roofing absorption
≤ 0.25% for Grade S1 (ASTM C406)
Grading
EN 12326 (EU/UK), ASTM C406 (US)
Finishes
Riven, honed, brushed
Products
Roof slates, tiles, cladding, ledgestone panels

Applications

Best used for

  • RoofingTop grades deliver 100-year service lives.
  • Rustic floorsRiven surfaces are naturally slip-resistant.
  • Wall cladding and ledgestoneStacked panels add depth to feature walls.
  • Lab benches and billiard tablesDense, flat and chemically stable.
  • Steps and landscapingDurable coping, steps and stepping stones.

Think twice for

  • Pyrite-rich stone in the rain. Unstable pyrite leaves rust streaks on roofs and paving.
  • Soft "slates". Some cheap slates are really shale or phyllite and flake.

Know the names

Popular varieties

  • Spanish Black

    Spain

    Blue-black roofing slate.

  • Welsh Blue-Grey

    UK

    The heritage roofing benchmark.

  • Brazilian Green

    Brazil

    Grey-green floor and roof slate.

  • Kund Multicolour

    India

    Rust, gold and grey bands.

  • Jak Black

    India

    Matte black riven tiles.

Origins

Which countries to source from

The producing countries that matter for slate, what each is known for, and a direct link to vendors there.
  • Spain flag

    Spain Leading source

    Supplies most of Europe's natural roofing slate

    • Galicia (Valdeorras)
    • León (Cabrera)
    Vendors in Spain
  • Brazil flag

    Brazil

    Minas Gerais slates for floors and roofs

    • Black, grey and green slates
    Vendors in Brazil
  • India flag

    India

    Colourful Himalayan and Rajasthan slates

    • Kund Multicolour
    • Jak Black
    • Deoli Green
    Vendors in India
  • China flag

    China

    Volume slate tiles and ledgestone panels

    • Rusty, black and multicolour ledgestone
    Vendors in China
  • UK flag

    UK

    Premium heritage roofing

    • Welsh slate (Penrhyn)
    Vendors in UK

Timing

Best time of year to buy

Order roofing slate in winter, ahead of the spring roofing season. Popular Spanish grades are allocated early and summer lead times stretch.

  1. Jan: best time to buy
  2. Feb: best time to buy
  3. Mar: best time to buy
  4. Apr: normal
  5. May: normal
  6. Jun: slower or pricier
  7. Jul: slower or pricier
  8. Aug: slower or pricier
  9. Sep: normal
  10. Oct: best time to buy
  11. Nov: best time to buy
  12. Dec: normal
Best time to buy Normal Slower or pricier
  • European roofing demand peaks from spring to early autumn.
  • Indian slate follows the sandstone calendar: best from October to March, slow in the monsoon.
  • Chinese ledgestone factories close for New Year; order by December for spring delivery.

Import costs

Tariffs and import duties

Base duties for the main import markets, the extra US surcharge by origin, and the trade remedies to check before you quote a landed price.

HS codes

  • 2514Slate, crude or merely cut
  • 6803Worked slate: roofing, tiles, articles

Base import duty (MFN)

  • United StatesFree to 3.3%Crude slate free; roofing slate 3.3%; other worked slate free.
  • European Union0% to 1.7%Crude slate duty-free; worked slate 1.7%.
  • United Kingdom0%Crude slate is duty-free; worked slate, including roofing tiles and other articles, is duty-free.

Importing into the US? Add the 2026 origin surcharge

Section 301 rates in force since 24 July 2026, stacked on the MFN rate above.

  • Spain flagSpain10% min.Section 301 (2026) tops the duty up to at least 10% in total; no surcharge if MFN is already higher.
  • Brazil flagBrazil+37.5% & 30137.5% Section 301 (2026) plus the legacy China Section 301 duty (25% on most stone and machinery lines), on top of MFN.
  • India flagIndia+10%Section 301 (2026) adds 10% on top of the MFN rate.
  • China flagChina+12.5% & 30112.5% Section 301 (2026) plus the legacy China Section 301 duty (25% on most stone and machinery lines), on top of MFN.
  • UK flagUK+10%Section 301 (2026) adds 10% on top of the MFN rate.
  • Roofing slate should come with EN 12326 (EU/UK) or ASTM C406 (US) test certificates.

Rates checked October 2026. Indicative rates for planning, not a customs ruling. Duties depend on the exact tariff line, origin, trade agreements and the rules in force on the day of entry. Confirm with a licensed customs broker before you price an order.

Before you order

Buying checklist

  1. 1Ask for EN 12326 or ASTM C406 grading. Look for W1, T1 and S1 codes (EN) or Grade S1 (ASTM).
  2. 2Check for pyrite: small metallic cubes that rust. Only stable, tested stone is acceptable on roofs.
  3. 3Use gauged (calibrated-back) tiles for thin-set floors; riven tiles vary in thickness.
  4. 4Buy the whole job in one order. Matching colour later is hard.
  5. 5Seal floor slate to deepen the colour and resist oil stains.

Price level: Indian and Chinese floor slates are inexpensive; top-grade Spanish and Welsh roofing slate is a premium product.

Vendor Network

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